UPDATE: According to Reuters, four officials have died in the violence in Benghazi, including the US ambassador to Libya.

Egyptian demonstrators stormed the US Embassies in Cairo and Benghazi on Tuesday, leaving one US official dead and one wounded.

Violence broke out in protest at an American amateur film allegedly produced by Coptic Christians now living in the United States that showed Muhammad standing trial.

Entitled Muhammad's Trial, the film, which was widely circulated on YouTube, depicts a mock trial of the prophet, and is reportedly linked to controversial Florida pastor Terry Jones, who gained notoriety in the US and throughout the Muslim world for threatening to burn a Koran.

Protesters destroy an American flag pulled down from the U.S. embassy in Cairo

The pastor was also behind “International Judge Muhammad Day”, an online show trial symbolically held on September 11, in which the Prophet was to "stand trial" before an international audience.

Following news of the film, Egyptians scaled the walls of the Embassy in Cairo in order to remove the American flag and replace it with an Islamic one, reading: "There is no God but Allah and Muhammad is the Prophet of Allah".

Speaking to the Huffington Post UK, Bel Trew, an Egypt-based journalist, said the Cairo unrest was instigated by a call from Salafist leader Wesam Abdel-Wareth, and ultraconservative Hekma television channel.

“The protesters also graffitied the Islamic slogan on the gates and some were, reportedly, seen burning the flag, a powerful image on the anniversary of 9/11,” said Trew.

Later on Tuesday, similar demonstrations broke out outside the Embassy in the eastern Libyan town of Benghazi, which lead to the death of one state department officer, confirmed by Secretary of State Hillary Clinton, who demanded President Mohammed el-Megarif "coordinate…to protect Americans in Libya."

"Some have sought to justify this vicious behavior as a response to inflammatory material posted on the Internet," said Clinton. "The United States deplores any intentional effort to denigrate the religious beliefs of others. Our commitment to religious tolerance goes back to the very beginning of our nation. But let me be clear: There is never any justification for violent acts of this kind."